Conventional mowers include a discharge outlet that allows grass clippings to exit the mower deck housing. A vacuum effect or updraft of air is created as air within the mower deck travels up and out the discharge outlet. The large vacuum effect created by these mowers lifts the grass for uniform cutting. Therefore, the cut quality achieved by these conventional mowers is relatively good. The clippings are either collected in a bag attached to the mower or are discharged across the ground. Disposing of bagged clippings is often viewed as inconvenient, and may be relatively costly. If the mower is adapted to discharge clippings through the discharge outlet and directly onto the ground, the need to dispose of bagged clippings is eliminated. This mode of operation has the disadvantage of leaving large clippings on top of the turf, which can be generally unsightly.
It is known to provide a mulching attachment which serves as a plug for blocking a mower's discharge outlet, and thereby causes recirculation of clippings within the mower deck such that they are re-cut many times and eventually become deposited on the ground. The need to bag the clippings is therefore eliminated. Furthermore, mulchers are designed to cut and re-cut clippings into very small particles which are then deposited into the turf. Mulchers are therefore intended to prevent large clippings from being left on top of the turf. However, when operating in tall wet grass these conventional mulching mower decks can become overloaded with grass clippings. When overloaded conventional mulching mechanisms tend to deposit clumps of large clippings on top of the turf. Furthermore, since conventional mulching mowers block the discharge outlet the vacuum effect or updraft of air is greatly decreased, which results in a reduction in cut quality.
Therefore, it would be desirable to provide a mulching mower which cuts and re-cuts grass clippings, deposits the small clippings into the turf, and which offer good cut quality. It would also be desirable to provide a mulching mower that does not leave unsightly clumps of large clippings on top of the turf when mowing in tall or wet grass which might otherwise cause overloading of the mower.